A communication system is formed, at a minimum, of a base station and a mobile station, which are interconnected by way of a communication channel. Information to be communicated by the base station (also referred to as cell site) to the mobile station is transmitted via the communication channel to the mobile station. A wide variety of different types of communication systems have been developed and are regularly utilized to effectuate communication of information between base stations and mobile stations.
A wireless communication system is an example of a communication system that has been made possible due to advancements in communication technologies. Various standards have been promulgated relating to various types of wireless communication systems, and various types of wireless, as well as other, communication systems have been constructed, corresponding to such standards. The IS-95 and IS-2000 interim standards, promulgated by the EIA/TIA, are exemplary of standards which pertain to a wireless communication system, utilizing code division multiple access (CDMA) communication techniques.
Enhanced 3rd Generation CDMA systems are currently being developed to address high speed Internet packet data services. Examples of such systems, which are the result of an evolution of IS-95 and IS2000, are 1XEV-DO (TIA/EIA/IS-856) and 1XEV-DV standards. These systems utilize both CDMA and some type of time division multiplexing communication techniques.
In an effort to port the Internet to the wireless communication system, 1XEV-DV and 1XEV-DO systems use a fat data pipe concept, which is shared among a number of users (mobile stations). The fat pipe, called the shared supplemental channel, is de-multiplexed into several code channels according to the usual CDMA access techniques. In the current proposal for 1XEV-DV, for example, the pipe is actually transmitted on up to twenty-eight Walsh codes of length thirty-two. And in the current proposal for 1XEV-DO, the pipe is actually transmitted on sixteen Walsh codes of length sixteen, all of which are used to carry a Packet Data Channel (PDCH).
In contrast to other communication systems, 1XEV-DV and 1XEV-DO systems both include a Packet Data Channel (PDCH) on the forward link between the base station and the mobile station. This channel has attributes that are drastically different than previous channels in IS-2000. One of the most notable attributes, from a physical layer perspective, is the adoption of high-order modulation (HOM). In this regard, 1XEV-DV and 1XEV-DO defines a modulation technique known as 16-QAM (Quadrature Amplitude Modulation). As will be appreciated by those skilled in the art, to demodulate this modulation format, knowledge of the QAM signal constellation amplitude/size is required. Current techniques for determining the constellation amplitude/size, however, can be undesirably complex, while requiring an undesirable amount of computing resources and not producing optimal performance in practical channel conditions.